The Protein Data Bank serves as the primary international repository for experimentally determined macromolecular structural data. Support for the Protein Data Bank over the past 5 years has been provided through an interagency consortium including the Department of Energy, National Institute of General Medical Sciences, the National Library o Medicine, and the National Science Foundation. The consortium was then expanded with the addition of the National Center for Research Resources, The National Cancer Institute, the National Institute of Biomedical Imaging and Bioengineering, and the National Institute of Neurological Disorders and Stroke.